Wettable hydrogels comprising acyclic polyamides

ABSTRACT

The present invention relates to biomedical devices, and particularly contact lenses comprising a polymer having entangled therein at least one acyclic polyamide.

RELATED APPLICATIONS

This patent application claims priority of a provisional application,U.S. Ser. No. 60/550,723 which was filed on Mar. 5, 2004.

BACKGROUND OF THE INVENTION

Contact lenses have been used commercially to improve vision since atleast the 1950s. The first contact lenses were made of hard materialsand as such were somewhat uncomfortable to users. Modern soft contactlenses are made of softer materials, typically hydrogels. Recently softcontact lenses made from silicone hydrogels have been introduced.Silicone hydrogel are water-swollen polymer networks that have highoxygen permeability. These lenses provide a good level of comfort tomany lens wearers, but there are some users who experience discomfortand excessive ocular deposits leading to reduced visual acuity whenusing these lenses. This discomfort and deposits has been attributed tothe hydrophobic character of the surfaces of lenses and the interactionof those surfaces with the protein, lipids and mucin and the hydrophilicsurface of the eye.

Others have tried to alleviate this problem by coating the surface ofsilicone hydrogel contact lenses with hydrophilic coatings, such asplasma coatings

Cyclic polyamides, such as polyvinylpyrollidone have been incorporatedinto both conventional and silicone containing hydrogel formulations andcontact lenses. Poly(meth)acrylamide and N-substitutedpoly(meth)acrylamides have been disclosed to be hydrophilic IPN agentswhich may be incorporated into conventional (non-silicone containing)hydrogels.

Modifying the surface of a polymeric article by adding polymerizablesurfactants to a monomer mix used to form the article has also beendisclosed. However, lasting in vivo improvements in wettability andreductions in surface deposits are not likely.

Polyvinylpyrrolidone (PVP) or poly-2-ethyl-2-oxazoline have been addedto a hydrogel forming composition to form an interpenetrating networkwhich shows a low degree of surface friction, a low dehydration rate anda high degree of biodeposit resistance. However, the hydrogelformulations disclosed are conventional hydrogels and there is nodisclosure on how to incorporate hydrophobic components, such assiloxane monomers, without causing insolubility of the hydrogel-formingcomposition.

While it may be possible to incorporate high molecular weight polymersas internal wetting agents into silicone hydrogel lenses, such polymerscan be difficult to solubilize in reaction mixtures which containsilicones.

Therefore it would be advantageous to find additional high molecularweight hydrophilic polymers which may be incorporated into a lensformulation to improve wettability of the lens without a surfacetreatment.

SUMMARY OF THE INVENTION

The present invention relates to a biomedical device comprising apolymer having entangled therein at least one acyclic polyamidecomprising repeating units of

Wherein X is a direct bond,

wherein R³ is a C1 to C3 alkyl group;

-   R¹ is selected from H, straight or branched, substituted or    unsubstituted C1 to C4 alkyl groups,-   R2 is selected from H, straight or branched, substituted or    unsubstituted C1 to C4 alkyl groups, amino groups having up to two    carbons, amide groups having up to four carbon atoms and alkoxy    groups having up to two carbons and wherein the number of carbon    atoms in R1 and R2 taken together is 8 or less.-   The present invention further relates to silicone hydrogels formed    from a reaction mixture comprising or consisting essentially of at    least one silicone containing component and at least one acyclic    polyamide comprising repeating units of Formula I

Wherein X is a direct bond,

wherein R³ is a C1 to C3 alkyl group;

-   R¹ is selected from H, straight or branched, substituted or    unsubstituted C1 to C4 alkyl groups,-   R² is selected from H, straight or branched, substituted or    unsubstituted C1 to C4 alkyl groups, amino groups having up to two    carbons, amide groups having up to four carbon atoms and alkoxy    groups having up to two carbons and wherein the number of carbon    atoms in R¹ and R² taken together is 8 or less, and preferably 6 or    less.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, a “biomedical device” is any article that is designed tobe used while either in or on mammalian tissues or fluid, and preferablyin or on human tissue or fluids. Examples of these devices include butare not limited to catheters, implants, stents, and ophthalmic devicessuch as intraocular lenses and contact lenses. The preferred biomedicaldevices are ophthalmic devices, particularly contact lenses, mostparticularly contact lenses made from silicone hydrogels.

As used herein, the terms “lens” and “ophthalmic device” refer todevices that reside in or on the eye. These devices can provide opticalcorrection, wound care, drug delivery, diagnostic functionality,cosmetic enhancement or effect or a combination of these properties. Theterm lens includes but is not limited to soft contact lenses, hardcontact lenses, intraocular lenses, overlay lenses, ocular inserts, andoptical inserts.

As used herein, the phrase “without a surface treatment” means that theexterior surfaces of the devices of the present invention are notseparately treated to improve the wettability of the device. Treatmentswhich may be foregone because of the present invention include, plasmatreatments, grafting, coating and the like. However, coatings whichprovide properties other than improved wettability, such as, but notlimited to antimicrobial coatings and the application of color or othercosmetic enhancement may be applied to devices of the present invention.

As used herein the term “silicone containing compatibilizing component”means reaction components which contain at least one silicone and atleast one hydroxyl group. Such components have been disclosed in U.S.Ser. Nos. 10/236,538 and 10/236,762.

The compositions of the present invention comprise, consist essentiallyand consist of at least one silicone containing component and at leastone acyclic polyamide. Acyclic polyamides of the present inventioncomprise pendant acyclic amide groups and are capable of associationwith hydroxyl groups. When the acyclic polyamides are incorporated intothe reactive mixture they have a weight average molecular weight of atleast about 100,000 Daltons, preferably greater than about 150,000; morepreferably between about 150,000 to about 2,000,000 Daltons, morepreferably still between about 300,000 to about 1,800,000 Daltons. Whenthe acyclic polyamides are incorporated into a solution in which amedical device formed from a hydrogel is stored, they have a weightaverage molecular weight of at least about 2,500 Daltons, preferablygreater than about 25,000; more preferably between about 100,000 toabout 2,000,000 Daltons, more preferably still between about 150,000 toabout 1,800,000 Daltons.

Alternatively, the molecular weight of hydrophilic polymers of theinvention can be also expressed by the K-value, based on kinematicviscosity measurements, as described in Encyclopedia of Polymer Scienceand Engineering, N-Vinyl Amide Polymers, Second edition, Vol 17, pgs.198-257, John Wiley & Sons Inc. When expressed in this manner, theacyclic polyamides of the present invention are those having K-values ofgreater than about 46 and preferably between about 46 and about 150.

The acyclic polyamides of the present invention are incorporated intothe hydrogel formulation of this invention without significant covalentbonding to the hydrogel. The absence of significant covalent bondingmeans that while a minor degree of covalent bonding may be present, itis incidental to the retention of the wetting agent in the hydrogelmatrix. Whatever incidental covalent bonding may be present, it wouldnot by itself be sufficient to retain the wetting agent in the hydrogelmatrix. Instead, the vastly predominating effect keeping the wettingagent associated with the hydrogel is entrapment. The polymer is“entrapped”, according to this specification, when it is physicallyretained within a hydrogel matrix. This is done via entanglement of thepolymer chain of the acyclic polyamide within the hydrogel polymermatrix. However, van der Waals forces, dipole-dipole interactions,electrostatic attraction and hydrogen bonding can also contribute tothis entrapment to a lesser extent.

The acyclic polyamides may be incorporated into the hydrogel by avariety of methods. For example, the acyclic polyamide may be added tothe reaction mixture such that the hydrogel polymerizes “around” theacyclic polyamide, forming a semi-interpenetrating network.Alternatively, the acyclic polyamide may be included in the solution inwhich the lens is packaged. The acyclic polyamide permeates into thelens. The packaged lens may be heat treated to increase the amount ofacyclic polyamide which permeates the lens. Suitable heat treatments,include, but are not limited to conventional heat sterilization cycles,which include temperatures of about 120° C. for times of about 20minutes. If heat sterilization is not used, the packaged lens may beseparately heat treated.

Examples of suitable acyclic polyamides include polymers and copolymerscomprising repeating units of Formula I

Wherein X is a direct bond,

wherein R³ is a C1 to C3 alkyl group;

R¹ is selected from H, straight or branched, substituted orunsubstituted C1to C4 alkyl groups,

R² is selected from H, straight or branched, substituted orunsubstituted C1 to C4 alkyl groups, amino groups having up to twocarbons, amide groups having up to 4 carbon atoms and alkoxy groupshaving up to two carbons and wherein the number of carbon atoms in R¹and R² taken together is 8, preferably 6 or less. As used hereinsubstituted alkyl groups include alkyl groups substituted with an amine,amide, ether or carboxy group.

In one preferred embodiment R¹ and R² are independently selected from H,and substituted or unsubstituted C1 to C2 alkyl groups and preferablyunsubstituted C1 to C2 alkyl groups.

In another preferred embodiment X is a direct bond, R¹ and R² areindependently selected from H, substituted or unsubstituted C1 to C2alkyl groups.

Preferably the acyclic polyamides of the present invention comprise amajority of the repeating unit of Formula I, and more preferably atleast about 80 mole % of the repeating unit of Formula I.

Specific examples of repeating units of Formula I include repeatingunits derived from N-vinyl-N-methylacetamide, N-vinylacetamide,N-vinyl-N-methylpropionamide, N-vinyl-N-methyl-2-methylpropionamide,N-vinyl-2-methylpropionamide, N-vinyl-N,N′-dimethylurea, and thefollowing acyclic amides:

Additional repeating units may be formed from monomers selected fromN-vinyl amides, acrylamides, hydroxyalkyl(meth)acrylates,alkyl(meth)acrylates or other hydrophilic monomers and siloxanesubstituted acrylates or methacrylates. Specific examples of monomerswhich may be used to form acyclic polyamides include asN-vinylpyrrolidone, N,N-dimethylacrylamide, 2-hydroxyethylmethacrylate,vinyl acetate, acrylonitrile,hydroxypropyl methacrylate, 2-hydroxyethylacrylate, methyl methacrylate and butyl methacrylate, methacryloxypropyltristrimethylsiloxysilane and the like and mixtures thereof. Preferredadditional repeating units monomers include of N-vinylpyrrolidone,N,N-dimethylacrylamide, 2-hydroxyethylmethacrylate and mixtures thereof.

In one embodiment the acyclic polyamide ispoly(N-vinyl-N-methylacetamide).

The acyclic polyamides may be used in amounts from about 1 to about 15weight percent, more preferably about 3 to about 15 percent, mostpreferably about 5 to about 12 percent, all based upon the total of allreactive components.

In one embodiment, the hydrogels of the present invention furthercomprise one or more silicone-containing components and, optionally oneor more hydrophilic components. The silicone-containing and hydrophiliccomponents used to make the polymer of this invention can be any of theknown components used in the prior art to make silicone hydrogels. Theseterms silicone-containing component and hydrophilic component are notmutually exclusive, in that, the silicone-containing component can besomewhat hydrophilic and the hydrophilic component can comprise somesilicone, because the silicone-containing component can have hydrophilicgroups and the hydrophilic components can have silicone groups.

Further, silicone-containing component(s) and hydrophilic component(s)can be reacted prior to polymerization to form a prepolymer which islater polymerized in the presence of a diluent to form the polymer ofthis invention. When prepolymers or macromers are used, it is preferredto polymerize at least one silicone-containing monomer and at least onehydrophilic monomer in the presence of the diluent, wherein thesilicone-containing monomers and the hydrophilic monomers differ. Theterm “monomer” used herein refers to low molecular weight compounds(i.e. typically having number average molecular weights less than 700)that can be polymerized. Thus, it is understood that the terms“silicone-containing components” and “hydrophilic components” includemonomers, macromonomers and prepolymers.

A silicone-containing component is one that contains at least one[—Si—O—Si] group, in a monomer, macromer or prepolymer. Preferably, theSi and attached O are present in the silicone-containing component in anamount greater than 20 weight percent, and more preferably greater than30 weight percent of the total molecular weight of thesilicone-containing component. Useful silicone-containing componentspreferably comprise polymerizable functional groups such as acrylate,methacrylate, acrylamide, methacrylamide, N-vinyl lactam, N-vinylamide,and styryl functional groups. Examples of silicone-containing componentswhich are useful in this invention may be found in U.S. Pat. Nos.3,808,178; 4,120,570; 4,136,250; 4,153,641; 4,740,533; 5,034,461 and5,070,215, and EP080539. All of the patents cited herein are herebyincorporated in their entireties by reference. These references disclosemany examples of olefinic silicone-containing components.

Further examples of suitable silicone-containing monomers arepolysiloxanylalkyl(meth)acrylic monomers represented by the followingformula:

wherein: R denotes H or lower alkyl; X denotes O or NR⁴; each R⁴independently denotes hydrogen or methyl,

each R¹-R³ independently denotes a lower alkyl radical or a phenylradical, and n is 1 or 3 to 10.

Examples of these polysiloxanylalkyl(meth)acrylic monomers include

-   methacryloxypropyl tris(trimethylsiloxy)silane,-   methacryloxymethylpentamethyldisiloxane,-   methacryloxypropylpentamethyldisiloxane,-   methyldi(trimethylsiloxy)methacryloxypropyl silane, and-   methyldi(trimethylsiloxy)methacryloxymethyl silane.    Methacryloxypropyl tris(trimethylsiloxy)silane is the most    preferred.

One preferred class of silicone-containing components is apoly(organosiloxane)prepolymer represented by Formula III: Formula III

wherein each A independently denotes an activated unsaturated group,such as an ester or amide of an acrylic or a methacrylic acid or analkyl or aryl group (providing that at least one A comprises anactivated unsaturated group capable of undergoing radicalpolymerization); each of R⁵, R⁶, R⁷ and R⁸ are independently selectedfrom the group consisting of a monovalent hydrocarbon radical or ahalogen substituted monovalent hydrocarbon radical having 1 to 18 carbonatoms which may have ether linkages between carbon atoms;

R⁹ denotes a divalent hydrocarbon radical having from 1 to 22 carbonatoms, and

m is 0 or an integer greater than or equal to 1, and preferably 5 to400, and more preferably 10 to 300. One specific example is α,ω-bismethacryloxypropyl poly-dimethylsiloxane. Another preferred exampleis mPDMS (monomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane).

Another useful class of silicone containing components includessilicone-containing vinyl carbonate or vinyl carbamate monomers of thefollowing formula:

wherein: Y denotes O, S. or NH; R^(Si) denotes a silicone-containingorganic radical; R denotes hydrogen or methyl; d is 1, 2, 3 or 4; and qis 0 or 1. Suitable silicone-containing organic radicals R^(Si) includethe following:

wherein:

Q denotes

wherein p is 1 to 6; R10 denotes an alkyl radical or a fluoroalkylradical having 1 to 6 carbon atoms; e is 1 to 200; q′ is 1, 2, 3 or 4;and s is 0, 1, 2, 3, 4 or 5.

The silicone-containing vinyl carbonate or vinyl carbamate monomersspecifically include:1,3-bis[4-(vinyloxycarbonyloxy)but-1-yl]tetramethyl-disiloxane;3-(vinyloxycarbonylthio)propyl-[tris(trimethylsiloxy)silane];3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbamate;trimethylsilylethyl vinyl carbonate; trimethylsilylmethyl vinylcarbonate, and

Another class of silicone-containing components includes polyurethanecompounds of the following formulae:

(*D*A*D*G)_(a)*D*D*E¹;   Formulae V-VII

E(*D*G*D*A)_(a)*D*G*D*E¹ or;

E(*D*A*D*G)_(a)*D*A*D*E¹

wherein:

D denotes an alkyl diradical, an alkyl cycloalkyl diradical, acycloalkyl diradical, an aryl diradical or an alkylaryl diradical having6 to 30 carbon atoms,

G denotes an alkyl diradical, a cycloalkyl diradical, an alkylcycloalkyl diradical, an aryl diradical or an alkylaryl diradical having1 to 40 carbon atoms and which may contain ether, thio or amine linkagesin the main chain;

* denotes a urethane or ureido linkage;

_(a) is at least 1;

A denotes a divalent polymeric radical of formula:

R¹¹ independently denotes an alkyl or fluoro-substituted alkyl grouphaving 1 to10 carbon atoms which may contain ether linkages betweencarbon atoms; y is at least 1; and p provides a moiety weight of 400 to10,000; each of E and E¹ independently denotes a polymerizableunsaturated organic radical represented by formula:

wherein: R¹² is hydrogen or methyl; R¹³ is hydrogen, an alkyl radicalhaving 1 to 6 carbon atoms, or a —CO—Y—R¹⁵ radical wherein Y is —O—,Y—S—or —NH—; R¹⁴ is a divalent radical having 1 to 12 carbon atoms; Xdenotes —CO— or —OCO—; Z denotes —O— or —NH—; Ar denotes an aromaticradical having 6 to 30 carbon atoms; w is 0 to 6; x is 0 or 1; y is 0 or1; and z is 0 or 1.

A preferred silicone-containing component is represented by thefollowing formula:

wherein R¹⁶ is a diradical of a diisocyanate after removal of theisocyanate group, such as the diradical of isophorone diisocyanate.Another preferred silicone containing macromer is compound of formula X(in which x+y is a number in the range of 10 to 30) formed by thereaction of fluoroether, hydroxy-terminated polydimethylsiloxane,isophorone diisocyanate and isocyanatoethylmethacrylate.

Other silicone-containing components suitable for use in this inventioninclude those described is WO 96/31792 such as macromers containingpolysiloxane, polyalkylene ether, diisocyanate, polyfluorinatedhydrocarbon, polyfluorinated ether and polysaccharide groups. U.S. Pat.Nos. 5,321,108; 5,387,662 and 5,539,016 describe polysiloxanes with apolar fluorinated graft or side group having a hydrogen atom attached toa terminal difluoro-substituted carbon atom. Such polysiloxanes can alsobe used as the silicone monomer in this invention. The hydrophilicsiloxanyl methacrylate monomers and polysiloxane-dimethacrylatemacromers described in US 2004/0192872 can also be used in thisinvention.

Hydrophilic components include those which are capable of providing atleast about 20% and preferably at least about 25% water content to theresulting lens when combined with the remaining reactive components.When present, suitable hydrophilic components may be present in amountsup to about 60 weight %, preferably between about 10 to about 60 weight%, more preferably between about 15 to about 50 weight % and morepreferably still between about 20 to about 40 weight %, all based uponthe weight of all reactive components. The hydrophilic monomers that maybe used to make the polymers of this invention have at least onepolymerizable double bond and at least one hydrophilic functional group.Examples of polymerizable double bonds include acrylic, methacrylic,acrylamido, methacrylamido, fumaric, maleic, styryl, isopropenylphenyl,O-vinylcarbonate, O-vinylcarbamate, allylic, O-vinylacetyl andN-vinyllactam and N-vinylamido double bonds. Such hydrophilic monomersmay themselves be used as crosslinking agents. “Acrylic-type” or“acrylic-containing” monomers are those monomers containing the acrylicgroup (CR′H═CRCOX) wherein R is H or CH₃, R′ is H, alkyl or carbonyl,and X is O or N, which are also known to polymerize readily, such asN,N-dimethylacrylamide (DMA), 2-hydroxyethyl acrylate, glycerolmethacrylate, 2-hydroxyethyl methacrylamide, polyethyleneglycolmonomethacrylate, methacrylic acid, acrylic acid and mixtures thereof.

Hydrophilic vinyl-containing monomers which may be incorporated into thehydrogels of the present invention include monomers such as N-vinyllactams (e.g. N-vinyl pyrrolidone (NVP)), N-vinyl-N-methyl acetamide,N-vinyl-N-ethyl acetamide, N-vinyl-N-ethyl formamide, N-vinyl formamide,N-2-hydroxyethyl vinyl carbamate, N-carboxy-B-alanine N-vinyl ester,with NVP being preferred.

Other hydrophilic monomers that can be employed in the invention includepolyoxyethylene polyols having one or more of the terminal hydroxylgroups replaced with a functional group containing a polymerizabledouble bond. Examples include polyethylene glycol with one or more ofthe terminal hydroxyl groups replaced with a functional group containinga polymerizable double bond. Examples include polyethylene glycolreacted with one or more molar equivalents of an end-capping group suchas isocyanatoethyl methacrylate (“IEM”), methacrylic anhydride,methacryloyl chloride, vinylbenzoyl chloride, or the like, to produce apolyethylene polyol having one or more terminal polymerizable olefinicgroups bonded to the polyethylene polyol through linking moieties suchas carbamate or ester groups.

Still further examples are the hydrophilic vinyl carbonate or vinylcarbamate monomers disclosed in U.S. Pat. No.5,070,215, and thehydrophilic oxazolone monomers disclosed in U.S. Pat. No. 4,190,277.Other suitable hydrophilic monomers will be apparent to one skilled inthe art.

More preferred hydrophilic monomers which may be incorporated into thepolymer of the present invention include hydrophilic monomers such asN,N-dimethyl acrylamide (DMA), 2-hydroxyethyl acrylate, glycerolmethacrylate, 2-hydroxyethyl methacrylamide, N-vinylpyrrolidone (NVP),N-vinyl-N-methyl acetamide and polyethyleneglycol monomethacrylate.

Most preferred hydrophilic monomers include DMA, NVP and mixturesthereof.

When the acyclic polyamides of the present invention are incorporatedinto a silicone hydrogel formulation, it may be desirable to include atleast one a hydroxyl containing component to help compatibilize theacyclic polyamide of the present invention and the silicone containingcomponents. The hydroxyl containing component that may be used to makethe polymers of this invention have at least one polymerizable doublebond and at least one hydrophilic functional group. Examples ofpolymerizable double bonds include acrylic, methacrylic, acrylamido,methacrylamido, fumaric, maleic, styryl, isopropenylphenyl,O-vinylcarbonate, O-vinylcarbamate, allylic, O-vinylacetyl andN-vinyllactam and N-vinylamido double bonds. The hydroxyl containingcomponent may also act as a crosslinking agent. In addition the hydroxylcontaining component comprises a hydroxyl group. This hydroxyl group maybe a primary, secondary or tertiary alcohol group, and may be located onan alkyl or aryl group. Examples of hydroxyl containing monomers thatmay be used include but are not limited to 2-hydroxyethyl methacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylamide, 2-hydroxyethylacrylamide, N-(2-hydroxyethyl)-O-vinyl carbamate, 2-hydroxyethyl vinylcarbonate, 2-hydroxypropyl methacrylate, hydroxyhexyl methacrylate,hydroxyoctyl methacrylate and other hydroxyl functional monomers asdisclosed in U.S. Pat. Nos. 5,006,622; 5,070,215; 5,256,751 and5,311,223. Preferred hydrophilic components include 2-hydroxyethylmethacrylate. The hydroxyl containing component may also includesilicone or siloxane functionalities, such as thehydroxyl-functionalized silicone containing monomers disclosed inWO03/022321, the disclosure of which is incorporated herein byreference.

Alternatively the acyclic polyamides may be included in hydrophilichydrogels which do not comprise silicone. Generally these hydrogels aremade from the hydrophilic monomers listed above. Commercially availablehydrogel formulations include, but are not limited to etafilcon,polymacon, vifilcon, genfilcon A and lenefilcon A.

Generally the reactive components are mixed in a diluent to form areaction mixture. Suitable diluents are known in the art. For siliconehydrogels suitable diluents are disclosed in WO 03/022321, thedisclosure of which is incorporated herein by reference.

Classes of suitable diluents for silicone hydrogel reaction mixturesinclude alcohols having 2 to 20 carbons, amides having 10 to 20 carbonatoms derived from primary amines and carboxylic acids having 8 to 20carbon atoms. In some embodiments primary and tertiary alcohols arepreferred. Preferred classes include alcohols having 5 to 20 carbons andcarboxylic acids having 10 to 20 carbon atoms.

Specific diluents which may be used include 1-ethoxy-2-propanol,diisopropylaminoethanol, isopropanol, 3,7-dimethyl-3-octanol, 1-decanol,1-dodecanol, 1-octanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol,2-octanol, 3-methyl-3-pentanol, tert-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-propanol, 1-propanol,ethanol, 2-ethyl-1-butanol,(3-acetoxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane,1-tert-butoxy-2-propanol, 3,3-dimethyl-2-butanol, tert-butoxyethanol,2-octyl-1-dodecanol, decanoic acid, octanoic acid, dodecanoic acid,2-(diisopropylamino)ethanol mixtures thereof and the like.

Preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,3-methyl-3-pentanol, 2-pentanol, t-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, ethanol,3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, decanoic acid, octanoicacid, dodecanoic acid, mixtures thereof and the like.

More preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,1-dodecanol, 3-methyl-3-pentanol, 1-pentanol, 2-pentanol, t-amylalcohol, tert-butanol, 2-butanol, 1-butanol, 2-methyl-2-pentanol,2-ethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, mixturesthereof and the like.

Suitable diluents for non-silicone containing reaction mixtures includeglycerin, ethylene glycol, ethanol, methanol, ethyl acetate, methylenechloride, polyethylene glycol, polypropylene glycol, low molecularweight PVP, such as disclosed in U.S. Pat. Nos. 4,018,853, U.S. Pat. No.4,680,336 and U.S. Pat. No. 5,039,459, including, but not limited toboric acid esters of dihydric alcohols, combinations thereof and thelike.

Mixtures of diluents may be used. The diluents may be used in amounts upto about 55% by weight of the total of all components in the reactionmixture. More preferably the diluent is used in amounts less than about45% and more preferably in amounts between about 15 and about 40% byweight of the total of all components in the reaction mixture.

It is generally necessary to add one or more cross-linking agents, alsoreferred to as cross-linking monomers, to the reaction mixture, such asethylene glycol dimethacrylate (“EGDMA”), trimethylolpropanetrimethacrylate (“TMPTMA”), glycerol trimethacrylate, polyethyleneglycol dimethacrylate (wherein the polyethylene glycol preferably has amolecular weight up to, e.g., about 5000), and other polyacrylate andpolymethacrylate esters, such as the end-capped polyoxyethylene polyolsdescribed above containing two or more terminal methacrylate moieties.The cross-linking agents are used in the usual amounts, e.g., from about0.000415 to about 0.0156 mole per 100 grams of reactive components inthe reaction mixture. (The reactive components are everything in thereaction mixture except the diluent and any additional processing aidswhich do not become part of the structure of the polymer.)Alternatively, if the hydrophilic monomers and/or thesilicone-containing monomers act as the cross-linking agent, theaddition of a crosslinking agent to the reaction mixture is optional.Examples of hydrophilic monomers which can act as the crosslinking agentand when present do not require the addition of an additionalcrosslinking agent to the reaction mixture include polyoxyethylenepolyols described above containing two or more terminal methacrylatemoieties.

An example of a silicone-containing monomer which can act as acrosslinking agent and, when present, does not require the addition of acrosslinking monomer to the reaction mixture includes a,w-bismethacryloxypropyl polydimethylsiloxane.

The reaction mixture may contain additional components such as, but notlimited to, UV absorbers, medicinal agents, antimicrobial compounds,reactive tints, pigments, copolymerizable and nonpolymerizable dyes,release agents and combinations thereof.

A polymerization catalyst is preferably included in the reactionmixture. The polymerization initiators includes compounds such as laurylperoxide, benzoyl peroxide, isopropyl percarbonate,azobisisobutyronitrile, and the like, that generate free radicals atmoderately elevated temperatures, and photoinitiator systems such asaromatic alpha-hydroxy ketones, alkoxyoxybenzoins, acetophenones,acylphosphine oxides, bisacylphosphine oxides, and a tertiary amine plusa diketone, mixtures thereof and the like. Illustrative examples ofphotoinitiators are 1-hydroxycyclohexyl phenyl ketone,2-hydroxy-2-methyl-1-phenyl-propan-1-one,bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide(DMBAPO), bis(2,4,6-trimethylbenzoyl)-phenyl phosphineoxide (Irgacure819), 2,4,6-trimethylbenzyldiphenyl phosphine oxide and2,4,6-trimethylbenzoyl diphenylphosphine oxide, benzoin methyl ester anda combination of camphorquinone and ethyl 4-(N,N-dimethylamino)benzoate.Commercially available visible light initiator systems include Irgacure819, Irgacure 1700, Irgacure 1800, Irgacure 819, Irgacure 1850 (all fromCiba Specialty Chemicals) and Lucirin TPO initiator (available fromBASF). Commercially available UV photoinitiators include Darocur 1173and Darocur 2959 (Ciba Specialty Chemicals). These and otherphotoinitators which may be used are disclosed in Volume III,Photoinitiators for Free Radical Cationic & Anionic Photopolymerization,2^(nd) Edition by J. V. Crivello& K. Dietliker; edited by G. Bradley;John Wiley and Sons; New York; 1998, which is incorporated herein byreference. The initiator is used in the reaction mixture in effectiveamounts to initiate photopolymerization of the reaction mixture, e.g.,from about 0.1 to about 2 parts by weight per 100 parts of reactivemonomer. Polymerization of the reaction mixture can be initiated usingthe appropriate choice of heat or visible or ultraviolet light or othermeans depending on the polymerization initiator used. Alternatively,initiation can be conducted without a photoinitiator using, for example,e-beam. However, when a photoinitiator is used, the preferred initiatorsare bisacylphosphine oxides, such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819®) or a combination of 1-hydroxycyclohexylphenyl ketone and bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentylphosphine oxide (DMBAPO), and the preferred method of polymerizationinitiation is visible light. The most preferred isbis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Irgacure 819®).

The preferred range of silicone-containing monomer present in thereaction mixture is from about 5 to 95 weight percent, more preferablyabout 30 to 85 weight percent, and most preferably about 45 to 75 weightpercent of the reactive components in the reaction mixture. Thepreferred range of hydrophilic monomer present in the above invention isfrom about 5 to 80 weight percent, more preferably about 10 to 60 weightpercent, and most preferably about 20 to 50 weight percent of thereactive components in the reaction mixture. The preferred range ofdiluent present in the above invention is from about 2 to 70 weightpercent, more preferably about 5 to 50 weight percent, and mostpreferably about 15 to 40 weight percent of the total reaction mixture(including reactive and nonreactive components).

Preferred combinations of reactive components and diluents are thosehaving from about 25 to about 55 weight % silicone-containing monomer,about 20 to about 40 weight % hydrophilic monomer, from about 5 to about20 weight % of an hydroxyl containing component, from about 0.2 to about3 weight % of a crosslinking monomer, from about 0 to about 3 weight %of a UV absorbing monomer, from about 2 to about 10 weight % of anacyclic polyamide (all based upon the weight % of all reactivecomponents) and about 20 to about 50 weight % (weight % of allcomponents, both reactive and non-reactive) of one or more of theclaimed diluents.

The reaction mixtures of the present invention can be formed by any ofthe methods known to those skilled in the art, such as shaking orstirring, and used to form polymeric articles or devices by knownmethods.

For example, the biomedical devices of the invention may be prepared bymixing reactive components and the diluent(s) with a polymerizationinitator and curing by appropriate conditions to form a product that canbe subsequently formed into the appropriate shape by lathing, cuttingand the like. Alternatively, the reaction mixture may be placed in amold and subsequently cured into the appropriate article.

Various processes are known for processing the reaction mixture in theproduction of contact lenses, including spincasting and static casting.Spincasting methods are disclosed in U.S. Pat. Nos. 3,408,429 and3,660,545, and static casting methods are disclosed in U.S. Pat. Nos.4,113,224 and 4,197,266. The preferred method for producing contactlenses comprising the polymer of this invention is by the molding of thesilicone hydrogels, which is economical, and enables precise controlover the final shape of the hydrated lens. For this method, the reactionmixture is placed in a mold having the shape of the final desiredsilicone hydrogel, i.e., water-swollen polymer, and the reaction mixtureis subjected to conditions whereby the monomers polymerize, to therebyproduce a polymer/diluent mixture in the shape of the final desiredproduct. Then, this polymer/diluent mixture is treated with a solvent toremove the diluent and ultimately replace it with water, producing asilicone hydrogel having a final size and shape which are quite similarto the size and shape of the original molded polymer/diluent article.This method can be used to form contact lenses and is further describedin U.S. Pat. Nos. 4,495,313; 4,680,336; 4,889,664; and 5,039,459,incorporated herein by reference.

In another embodiment, the lens is formed without acyclic polymer andafter formation, is placed in a solution comprising acyclic polyamide.In this embodiment the lens is formed from hydrophilic polymers inamounts between about 40 and 100 weight % of the reactive components.Suitable solutions include packing solution, storing solution andcleaning solutions. Preferably the lens is placed in a packing solutioncomprising said acyclic polyamide. The acyclic polyamide is present inthe solution in amounts between about 0.001 and about 10%, preferablybetween about 0.005 and about 2% and more preferably between about 0.01and about 0.5 weight %, based upon all components in the solution.

The packing solutions of the invention may be any water-based solutionthat is used for the storage of contact lenses. Typical solutionsinclude, without limitation, saline solutions, other buffered solutions,and deionized water. The preferred aqueous solution is saline solutioncontaining salts including, without limitation, sodium chloride, sodiumborate, sodium phosphate, sodium hydrogenphosphate, sodiumdihydrogenphosphate, or the corresponding potassium salts of the same.These ingredients are generally combined to form buffered solutions thatinclude an acid and its conjugate base, so that addition of acids andbases cause only a relatively small change in pH. The buffered solutionsmay additionally include 2-(N-morpholino)ethanesulfonic acid (MES),sodium hydroxide, 2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol,n-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid, citric acid,sodium citrate, sodium carbonate, sodium bicarbonate, acetic acid,sodium acetate, ethylenediamine tetraacetic acid and the like andcombinations thereof. Preferably, the solution is a borate buffered orphosphate buffered saline solution. The solutions may also include knownadditional components such as viscosity adjusting agents, antimicrobialagents, polyelectrolytes, stabilizers, chelants, antioxidants,combinations thereof and the like.

The device is contacted with the acyclic polyamide under conditionssufficient to incorporate a lubricious effective amount of said acyclicpolyamide. As used herein, a lubricious effective amount, is an amountnecessary to impart a level of lubricity which may be felt manually(such as by rubbing the device between one's fingers) or when the deviceis used. It has been found that in one embodiment, where the device is asoft contact lens, when amounts of acyclic polyamide as little as 10 ppmprovide improved lens “feel”. Amounts of acyclic polyamide greater thanabout 50 pm, and more preferably amounts greater than about 100 ppm,(measured via extraction in 2 ml of a 1:1DMF:deionized water solution,for 72 hours) add a more pronounced improvement in feel. The packagedlens may be heat treated to increase the amount of acyclic polyamidewhich permeates and becomes entangled in the lens. Suitable heattreatments, include, but are not limited to conventional heatsterilization cycles, which include temperatures of about 120° C. fortimes of about 20 minutes and may be conducted in an autoclave. If heatsterilization is not used, the packaged lens may be separately heattreated. Suitable temperatures for separate heat treatment include atleast about 40° C., and preferably between about 50° C. and the boilingpoint of the solution. Suitable heat treatment times include at leastabout 10 minutes. It will be appreciated that higher temperatures willrequire less treatment time.

The biomedical devices, and particularly ophthalmic lenses of thepresent invention have a balance of properties which makes themparticularly useful. Such properties include clarity, water content,oxygen permeability and contact angle. Thus, in one embodiment, thebiomedical devices are contact lenses having a water content of greaterthan about 17%, preferably greater than about 20% and more preferablygreater than about 25%.

As used herein clarity means substantially free from visible haze.Preferably clear lenses have a haze value of less than about 150%, morepreferably less than about 100%.

Suitable oxygen permeabilities for silicone containing lenses arepreferably greater than about 40 barrer and more preferably greater thanabout 60 barrer.

Also, the biomedical devices, and particularly ophthalmic devices andcontact lenses have contact angles (advancing) which are less than about80°, preferably less than about 70° and more preferably less than about65°. In some preferred embodiments the articles of the present inventionhave combinations of the above described oxygen permeability, watercontent and contact angle. All combinations of the above ranges aredeemed to be within the present invention.

The non-limiting examples below further describe this invention.

The dynamic contact angle or DCA, was measured at 23° C., with boratebuffered saline, using a Wilhelmy balance. The wetting force between thelens surface and borate buffered saline is measured using a Wilhelmymicrobalance while the sample strip cut from the center portion of thelens is being immersed into the saline at a rate of 100 microns/sec. Thefollowing equation is used

F=2γp cos θ or θ=cos⁻¹(F/2γp)

where F is the wetting force, γ is the surface tension of the probeliquid, p is the perimeter of the sample at the meniscus and θ is thecontact angle. Typically, two contact angles are obtained from a dynamicwetting experiment—advancing contact angle and receding contact angle.Advancing contact angle is obtained from the portion of the wettingexperiment where the sample is being immersed into the probe liquid, andthese are the values reported herein. At least four lenses of eachcomposition are measured and the average is reported.

The water content was measured as follows: lenses to be tested wereallowed to sit in packing solution for 24 hours. Each of three test lenswere removed from packing solution using a sponge tipped swab and placedon blotting wipes which have been dampened with packing solution. Bothsides of the lens were contacted with the wipe. Using tweezers, the testlens were placed in a weighing pan and weighed. The two more sets ofsamples were prepared and weighed as above. The pan was weighed threetimes and the average is the wet weight.

The dry weight was measured by placing the sample pans in a vacuum ovenwhich has been preheated to 60° C. for 30 minutes. Vacuum was applieduntil at least 0.4 inches Hg is attained. The vacuum valve and pump wereturned off and the lenses were dried for four hours. The purge valve wasopened and the oven was allowed reach atmospheric pressure. The panswere removed and weighed. The water content was calculated as follows:

$\begin{matrix}{{{Wet}\mspace{14mu} {weight}} = {{{combined}\mspace{14mu} {wet}\mspace{14mu} {weight}\mspace{14mu} {of}\mspace{14mu} {pan}\mspace{14mu} {and}\mspace{14mu} {lenses}} -}} \\{{weight}\mspace{14mu} {of}\mspace{14mu} {weighing}\mspace{14mu} {pan}}\end{matrix}$ $\begin{matrix}{{{Dry}\mspace{14mu} {weight}} = {{{combined}\mspace{14mu} {dry}\mspace{14mu} {weight}\mspace{14mu} {of}\mspace{14mu} {pan}\mspace{14mu} {and}\mspace{14mu} {lens}} -}} \\{{weight}\mspace{14mu} {of}\mspace{14mu} {weighing}\mspace{14mu} {pan}}\end{matrix}$$\mspace{85mu} {{\% \mspace{14mu} {water}\mspace{14mu} {content}} = {\frac{\left( {{{wet}\mspace{14mu} {weight}} - {{dry}\mspace{14mu} {weight}}} \right.}{{wet}\mspace{14mu} {weight}} \times 100}}$

The average and standard deviation of the water content are calculatedfor the samples are reported.

Modulus was measured by using the crosshead of a constant rate ofmovement type tensile testing machine equipped with a load cell that islowered to the initial gauge height. A suitable testing machine includesan Instron model 1122. A dog-bone shaped sample having a 0.522 inchlength, 0.276 inch “ear” width and 0.213 inch “neck” width was loadedinto the grips and elongated at a constant rate of strain of 2 in/min.until it broke. The initial gauge length of the sample (Lo) and samplelength at break (Lf) were measured. Twelve specimens of each compositionwere measured and the average is reported. Tensile modulus was measuredat the initial linear portion of the stress/strain curve.

The dynamic coefficient of friction of the contact lens was measuredusing a Tribometer, Model UMT-2 unit, with a pin-on-disk sample mount.The contact lens sample was removed from its packing solution and placedon the tip of the “pin” with the center of the lens on the pin tip andpressed against a highly polished stainless steel disk moving at aconstant speed of either 10 or 15 cm/sec. Loads of 3, 5, 10 and 20 gwere used. The duration at each load was 25 seconds and all measurementswere taken at ambient temperature. The resistant frictional force wasmeasured and was used to calculate the coefficient of friction using thefollowing formula:

=(F−f′)/N, where

=coefficient of friction

F=measured frictional force, f+f′

f=actual frictional force

f′=experimental artifacts due lens deformation, such as dehydration andinterfacial surface tension forces, elasticity, etc.

N=normal load

Seven lenses were tested for each lens type. The coefficient of frictionwere averaged and reported.

Haze is measured by placing a hydrated test lens in borate bufferedsaline in a clear 20×40×10 mm glass cell at ambient temperature above aflat black background, illuminating from below with a fiber optic lamp(Titan Tool Supply Co. fiber optic light with 0.5″ diameter light guideset at a power setting of 4-5.4) at an angle 66° normal to the lenscell, and capturing an image of the lens from above, normal to the lenscell with a video camera (DVC 1300C:19130 RGB camera with Navitar TVZoom 7000 zoom lens) placed 14 mm above the lens platform. Thebackground scatter is subtracted from the scatter of the lens bysubtracting an image of a blank cell using EPIX XCAP V 1.0 software. Thesubtracted scattered light image is quantitatively analyzed, byintegrating over the central 10 mm of the lens, and then comparing to a−1.00 diopter CSI Thin Lens®, which is arbitrarily set at a haze valueof 100, with no lens set as a haze value of 0. Five lenses are analyzedand the results are averaged to generate a haze value as a percentage ofthe standard CSI lens.

Oxygen permeability (Dk) was determined by the polarographic methodgenerally described in ISO 9913-1: 1996(E), but with the followingvariations. The measurement is conducted at an environment containing2.1% oxygen. This environment is created by equipping the test chamberwith nitrogen and air inputs set at the appropriate ratio, for example1800 ml/min of nitrogen and 200 ml/min of air. The t/Dk is calculatedusing the adjusted p_(O2). Borate buffered saline was used. The darkcurrent was measured by using a pure humidified nitrogen environmentinstead of applying MMA lenses. The lenses were not blotted beforemeasuring. Four lenses were stacked instead of using lenses of variedthickness. A curved sensor was used in place of a flat sensor. Theresulting Dk value is reported in barrers.

The following abbreviations will be used throughout the Examples andhave the following meanings.

-   SiGMA 2-propenoic acid,    2-methyl-,2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propoxy]propyl    ester-   DMA N,N-dimethylacrylamide-   HEMA 2-hydroxyethyl methacrylate-   mPDMS 800-1000 MW (M_(n)) monomethacryloxypropyl terminated    mono-n-butyl terminated polydimethylsiloxane-   Norbloc 2-(2′-hydroxy-5-methacrylyloxyethylphenyl)-2H-benzotriazole-   CGI 1850 1:1 (wgt) blend of 1-hydroxycyclohexyl phenyl ketone and    bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide-   CGI 819 bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide-   PVP poly(N-vinyl pyrrolidone) (K value 90)-   Blue HEMA the reaction product of Reactive Blue 4 and HEMA, as    described in Example 4 of U.S. Pat. No. 5,944,853-   IPA isopropyl alcohol-   D30 3,7-dimethyl-3-octanol-   DI water deionized water-   TEGDMA tetraethyleneglycol dimethacrylate-   PVMA poly(N-vinyl-N-methylacetamide) (prepared in Preparation 2)-   mPDMS-OH mono-(3-methacryloxy-2-hydroxypropyloxy)propyl terminated,    mono-butyl terminated polydimethylsiloxane (MW 1100) Prepared as in    Preparation 1-   acPDMS bis-3-acryloxy-2-hydroxypropyloxypropyl polydimethylsiloxane    (MW ˜1000), commercially available from Geleste, Inc, of Tullytown    Pa. under the name Polydimethylsiloxane acryloxy terminated DMS-U22.-   Macromer Prepared as described in US20030052424, Example 1-   TMPTMA trimethylolpropane trimethacrylate-   BAGE boric acid ester of glycerin-   MAA methacrylic acid-   Irgacure 1700 A 75/25% (wt) blend of    2-hydroxy-2-methyl-1-phenyl-propan-1-one and    bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide-   Zeonor Cyclo olefin thermoplastic polymer from Nippon Zeon Co., Ltd.

Preparation 1

A three neck, 500 mL round bottom flask equipped with a magneticstirrer, reflux condensor w/drying tube, and a thermocouple was chargedwith 5.0 g (0.054 mole) dry lithium methacrylate. Methacrylic acid (50.0g, 0.584 mole) and 1.0 g p-methoxyphenol were added to the system, whichwas stirred while adding 200 g (about 0.20 mole) monoglycidoxypropylpolydimethylsiloxane (1000 M_(N)) to the flask. The reaction mixture washeated to 90° C. The mixture was heated for 15 hours at the giventemperature, allowed to cool to ambient conditions, and diluted with 250mL of ethyl acetate.

The organics were washed two times with 250 mL of 0.5N aqueous sodiumhydroxide. Once all the methacrylic acid present in the mixture wasneutralized, separation of the two layers dramatically slowed down. Thethird and fourth washes were performed using an aqueous solution of 0.5Nsodium hydroxide and 5% wt/volume sodium chloride in order to speed upthe separation process.

The organics were dried over 30 g of anhydrous sodium sulfate, andfiltered through a fritted glass funnel containing 75 g of flash gradesilica gel to remove any remaining salts in the system. The filtrate wasfreed of volatile material in a rotary evaporator at 55° C. under apressure of approximately 10 mbar.

The product, mono-(3-methacryloxy-2-hydroxypropyloxy)propyl terminated,mono-butyl terminated polydimethylsiloxane (MW 1100), was isolated as acolorless, clear liquid, 173.0 g, 79.7%.

Preparation 2

A solution of 20 ml N-vinyl-N-methylactamide, 20 g t-butanol and 15.5 mgazobisisobutyronitrile was degassed under vacuum, then heated to 75° C.for 16 hours to produce a viscous clear solution. 150 ml methanol wasadded and the mixture was transferred to a flask for rotary evaporation.After solvent was removed the polymer was dissolved in 100 ml methylenechloride and the polymer was precipitated by addition of about 1 Lhexane. The precipitate was squeezed to remove excess solvent, and driedunder vacuum overnight to produce 12.3 g PVMA as a white solid.

PVMA Preparation

A solution of 102.5 g N-methyl-N-vinylacetamide, 102.5 g t-butanol and46.5 mg 2,2′-azobisisobutylnitrile was deoxygenated by bubbling N₂ gasthrough it for one hour. The solution was heated to 75° C. with stirringunder N₂ for 16 hours. Solvent was evaporated from the resulting viscoussolution under vacuum. The resulting crude polymer was dissolved in 250ml CH₂Cl₂. 2.5 L hexane was added to precipitate polymer. The resultingsolid polymer mass was broken into pieces and dried under vacuum at 80°C. Molecular weight analysis by GPC showed M_(N) and M_(W) of 366,000and 556,000 respectively.

EXAMPLE 1

Contact lenses were made from the formulation listed in Table 1, below.

TABLE 1 Component Amount (g) Wt %^(a) mPDMS 4.771 30.98 SIGMA 4.30727.97 DMA 3.692 23.98 HEMA 0.929  6.03 TEGDMA 0.232  1.51 Norbloc 0.311 2.02 PVMA 1.082  7.03 CGI1850 0.074  0.48 D3O(diluent) 4.602 23.01^(b)^(a)Excluding diluent. ^(b)With respect to final reactive monomer mix.The monomer mixture was degassed by placing it under vacuum for 30minutes, and then used to make lenses in a nitrogen box (Zeonor frontcurves and polypropylene back curves, 50° C.) under four parallelvisible light Philips TL03 fluorescent lamps (30 minute cure). Thelenses were demolded manually and released in 70:30 IPA:DI water. Thelenses were then soaked in the following solutions for the timesindicated: 100% IPA (1 hour), 70:30 (vol) IPA:DI water (1 hour), 10:90IPA:DI water (1 hour), DI water (30 minutes). The lenses were stored infresh DI water. The lenses felt highly lubricious upon touching. Forhaze/DCA analysis (Table 2) lenses were autoclaved once (122.5° C., 30minutes) in 5.0 mL packing solution (borate buffered saline solution),while for mechanical properties and water content (Table 2), the lenseswere autoclaved once in packing solution containing 50 ppmmethylcellulose.

TABLE 2 Property Value Modulus (n = 5)  78 +/− 6 psi Elongation (n = 5)175 +/− 41% Water content (n = 9)  39 +/− 0.3% Haze (n = 5)  28 +/− 2%Advancing contact angle  42 +/− 18° (n = 4)

The properties in Table 2 demonstrate that PVMA can be incorporated intoa hydrogel composition to form an article having desirable mechanicalproperties.

EXAMPLE 2

Contact lenses were made from the formulation listed in Table 3, below.

TABLE 3 Component Amount used (g) Percent^(a) mPDMS-OH 0.87 52.57 acPDMS0.0427  2.58 DMA 0.394 23.81 HEMA 0.228 13.78 PVMA 0.116  7.01 CGI 8190.0041  0.25 Diluent: 1.351 44.95^(b) t-amyl alcohol ^(a)Excludingdiluent. ^(b)With respect to final reactive monomer mix.The monomer mixture was degassed under vacuum for 10 minutes, and thenused to make lenses in a nitrogen box (Zeonor front curves andpolypropylene back curves, 50° C.) under four parallel Philips TL03lamps (20 minute cure). The lenses were demolded manually and immersedin 30:70 IPA:DI water for 10 minutes. The lenses were released in ˜1 Lof boiling DI water, then transferred into packing solution. The lensesfelt highly lubricious. For DCA analysis lenses were autoclaved once(122.5° C., 30 minutes) in packing solution (5.0 mL). The advancingcontact angle was determined to be 45±5°.

COMPARATIVE EXAMPLE 3 AND EXAMPLE 4

Contact lenses were made from the formulations listed in Table 4, below.

TABLE 4 Comp. Ex. 3 Component (wt %)* Ex. 4 (wt %)* mPDMS-OH 50.00 49.97Macromer** 10.01  9.99 AcPDMS  2.02  2.00 DMA 20.00 20.05 HEMA  8.52 8.53 Norbloc  2.20  2.20 PVP 360,000  7.00 — PVMA —  7.02 CGI 819  0.25 0.25 Diluent: 45^(b) 45^(b) t-amyl alcohol ^(a)Excluding diluent.^(b)With respect to final reactive monomer mix. Macromer preparationdescribed in U.S. 2003/0052424The monomer mixes were filtered through 3 μm pore filter before use. Themonomer mixtures were degassed under vacuum for 15 minutes, and thenused to make lenses in a nitrogen box (Zeonor front curves andpolypropylene back curves, 50° C.) under four parallel Philips TL03lamps (30 minute cure). The lenses were demolded manually, released in˜1 L of boiling DI water, and then transferred into packing solution.Table 5 summarizes the properties of the lenses.

TABLE 5 Property Comp. Ex 3 Ex 4 Dk 171.5 —^(a) Modulus (n = 5)   88 +/−6 psi   92 +/− 10 psi Elongation (n = 5)  216 +/− 71%  232 +/− 30% Watercontent (n = 9) 35.6 +/− 0.5% 38.6 +/− 0.3% Haze (n = 5) 12.9 +/− 3.9%14.3 +/− 3.8% Advancing contact   59 +/− 7°   50 +/− 9° angle (n = 5)^(a)Did not measure.A study was conducted to assess the relative lubricity of lensescontaining PVP (Example 3) against lenses containing PVMA (Example 4).Seven subjects were masked from the identity of the lenses, and providedtwo vials containing a single lens. One vial contained a lens fromExample 3 (which contained PVP), and the other contained a lens fromExample 4 (containing PVMA). Each subject was asked to subjectively ratewhich lens felt more lubricious. All seven subjects picked the lens ofExample 4.

The dynamic coefficients of friction (COF) of the lenses of Examples 3and 4 were measured. The measurements were done using a polishedstainless steel as the reference surface and the test speed was at 15cm/s. All measurements were done in the lens own packing solution fromthe package.” The data in Table 6 show that incorporation of 7% PVMA insilicone hydrogel lenses provided more lubricious lenses thanincorporation of 7% PVP.

TABLE 6 Ex. # IWA COF C3 PVP 0.07 (0.01) 4 PVMA 0.038 (0.004)Table 6 shows that the lenses with PVMA have a COF of about half that ofPVP.

EXAMPLES 5 AND 6

1-Day Acuvue® brand contact lenses (commercially available from Johnson& Johnson Vision Care, Inc.) were washed in borate buffered saline (5rinses over 24 hours) to remove any residual TWEEN-80. The washed lenseswere packaged in with either 250 or 500 ppm PVMA in borate bufferedsaline solution, as shown in Table 7, below and sterilized (121° C., 30minutes). The contact angle was determined and is reported in Table 7.

TABLE 7 Ex. # [PVMA] (ppm) contact angle 5 250  74 (5) 6 500¹ 56 (9)Control — 78 (5)

The diameter of the lenses was measured once a week over a period offive weeks. The results are shown in Table 8.

TABLE 8 PVMA lens diameters PVMA Ex# (ppm) T (° C.) Week 1 Week 2 Week 3Week 4 Week 5 C 0 23° C. 14.17 14.14 14.18 14.17 14.18 C 0 55° C. 14.1514.12 14.20 14.15 14.16 5 250 23° C. 14.20 14.15 14.20 14.17 14.19 5 25055° C. 14.20 14.16 14.24 14.19 14.19 6 500 23° C. 14.19 14.19 14.2214.20 14.21 6 500 55° C. 14.23 14.19 14.28 14.20 14.20 C = control

The lens diameters for lenses at both PVMA concentrations remainedstable.

EXAMPLE 7

1-Day Acuvue® brand contact lenses (commercially available from Johnson& Johnson Vision Care, Inc.) were placed into borate-buffered salinecontaining 500 ppm PVMA, as described in Example 6. The lenses weresterilized multiple times, 30 minutes at 121° C. per cycle. The lenssurfaces had a lubricious feel after each sterilization cycle.

EXAMPLE 8

1-Day Acuvue® brand contact lenses (commercially available from Johnson& Johnson Vision Care, Inc.) were placed into plastic blister packagescontaining 950 μl each of a solution of 1000 ppm PVMA in borate-bufferedsaline. The packages were sealed, heat sterilized (121° C. for 30minutes) and clinically evaluated in a double-masked study. Ninepatients wore the lenses in both eyes for 3-4 days with overnightremoval and daily replacement, and then wore untreated 1-Day Acuvue®brand contact lenses for 3-4 days with overnight removal and dailyreplacement as a control. Patients were asked to rate the lens using aquestionnaire. The results are shown in Table 10.

TABLE 10 Preferred Preferred Ex. 11 Control Liked both Liked neitherOverall 67% 11% 22% 0% preference Comfort 67%  0% 33% 0% preference Endof day 78% 11% 11% 0% comfort Dryness 78% 11% 11% 0% preference Weartime 78% 11% 11% 0%

EXAMPLE 9 AND 10

The reactions mixtures listed in Table 11 were cured in a nitrogenatmosphere (Zeonor front curves and back curves, ˜75 mg per cavity, ˜50°C.) under Philips TLK 40W/03 lamps (4 minute cure). Lenses were releasedfrom the molds in DI water containing about 800 ppm Tween 80 at ˜70° C.for 150-210 minutes, and rinsed twice in DI water at about 45° C. for15-60 minutes and about180 minutes, respectively. The lenses werepackaged in 1·DAY ACUVUE® Brand contact lens bowl and foil in boratebuffered saline and sterilized (121° C., 30 minutes).

TABLE 11 Components Ex. 9 (wt %) Ex. 10 (wt %) HEMA 92.89 92.89 Norbloc7966 0.95 0.95 Irgacure 1700 1.34 1.34 EGDMA 0.77 0.77 TMPTMA 0.09 0.09MAA 1.94 1.94 Blue HEMA 0.02 0.02 PVP 360K 2.00 — PVMA — 2.00 Diluent52:48 52:48 BAGE Diluent 48% 48%

The feel of the lenses of Examples 9-10 were subjectively compared asfollows. The control was 1-Day Acuvue® brand contact lenses. Ten contactlens wearers were asked to rate their preference among different lenses(including the 1-DAY ACUVUE brand contact lens control) based on touchalone. A rating of “1” indicated that the lens was preferred, and basedupon feel alone, the tester would prefer that lens. A rating of “4” wasnot preferred. The contact lens wearers rating the lenses were permittedto rate more than one lens a 1. The average preference scores are listedin Table 12 below. Standard deviations are shown in parenthesis.

TABLE 12 Ex # Wetting agent Pref. score  9 PVP 2.6 (1)   10 PVMA 1.6(0.9) control — 3.3 (1)  

Thus, lenses formed from conventional hydrogel formulations whichcontain PVMA display tactile properties such as lubricity which arebetter than lenses which do not contain any wetting agent, and are atleast as good as lenses containing PVP.

1. (canceled)
 2. The method of claim 44 wherein the number of carbonatoms in R¹ and R² taken together is 6 or less.
 3. The method of claim44 wherein R¹ and R² are independently selected from H, substituted orunsubstituted C1 to C2 alkyl groups.
 4. The method of claim 44 whereinR¹ and R² are independently selected from H, unsubstituted C1 to C2alkyl groups.
 5. The method of claim 44 wherein X is a direct bond. 6.The method of claim 44 wherein R² is selected from straight or branchedunsubstituted C1 to C4 alkyl groups.
 7. The method of claim 44 whereinsaid solution comprises a mixture of acyclic polyamides.
 8. The methodof claim 6 wherein R¹ is selected from H, substituted or unsubstitutedC1 to C2 alkyl groups.
 9. The method of claim 44 wherein said acyclicpolyamide has a weight average molecular weight of at least about100,000.
 10. The method of claim 44 wherein said acyclic polyamide has aweight average molecular weight of at least about 300,000.
 11. Themethod of claim 44 wherein said acyclic polyamide has a weight averagemolecular weight of at least about 1,000,000.
 12. The method of claim 44wherein said acyclic polyamide is a copolymer comprising at least about50 mole % of the repeating unit of Formula I.
 13. The method of claim 44wherein said acyclic polyamide is a copolymer comprising at least about80 mole % of the repeating unit of Formula I.
 14. The method of claim 13wherein said copolymer further comprises repeating units derived frommonomers selected from the group consisting of N-vinylpyrrolidone,N,N-dimethylacrylamide, 2-hydroxyethylmethacrylate, vinyl acetate,acrylonitrile, siloxane substituted acrylates or methacrylates,alkyl(meth)acrylates and mixtures thereof.
 15. The method of claim 13wherein said copolymer further comprises repeating units derived frommonomers selected from the group consisting of N-vinylpyrrolidone,N,N-dimethylacrylamide, 2-hydroxyethylmethacrylate and mixtures thereof.16. The method of claim 44 wherein said repeating unit is derived from amonomer comprising N-ethylenyl-N-methylacetamide.
 17. The method ofclaim 44 wherein said acyclic polyamide ispoly(N-vinyl-N-methylacetamide).
 18. The method of claim 44 wherein saidhydrogel comprises at least one silicone-containing component and atleast one hydrophilic component. 19-43. (canceled)
 44. A methodcomprising contacting a biomedical device formed from a hydrogel with asolution comprising at least one acyclic polyamide comprising repeatingunits of Formula I

Wherein X is a direct bond,

wherein R³ is a C1 to C3 alkyl group; R¹ is selected from H, straight orbranched, substituted or unsubstituted C1 to C4 alkyl groups, R² isselected from H, straight or branched, substituted or unsubstituted C1to C4 alkyl groups, amino groups having up to two carbons, amide groupshaving up to four carbon atoms and alkoxy groups having up to twocarbons and wherein the number of carbon atoms in R¹ and R² takentogether is 8 or less, under conditions sufficient to incorporate alubricious effective amount of said acyclic polyamide in said biomedicaldevice.
 45. The method of claim 44 wherein said solution comprisesbetween about 0.001 and about 10% acyclic polyamide, based upon allcomponents in the solution.
 46. The method of claim 44 wherein saidsolution comprises between about 0.005 and about 2% acyclic polyamide,based upon all components in the solution.
 47. The method of claim 44wherein said contacting step further comprises heating.
 48. The methodof claim 47 wherein said heating comprising autoclaving.
 49. The methodof claim 44 wherein said device is a contact lens and said solution is apacking solution.